penalty 1/2% a month until paid (file timely because filing late and owing is another 4.5% per month for up to 5 months.
interest rates will vary.
The IRS interest rate is determined by the federal short-term rate plus 3%. Since the current federal short-term annual interest rate is 4.71%, the interest rate charged on late tax payments was 7.71% as of March 2024.
